What is the recommended dose of epinephrine (adrenaline) for an adult experiencing anaphylaxis?

Epinephrine Dosing for Adult Anaphylaxis

For adult anaphylaxis, administer 0.3-0.5 mg of epinephrine intramuscularly into the anterolateral aspect of the thigh, which can be repeated every 5-15 minutes as needed if symptoms persist. 1, 2

Initial Management

Intramuscular Administration

• First-line treatment: 0.3-0.5 mg (0.3-0.5 mL of 1:1000 solution) for adults ≥30 kg (66 lbs)
• Route: Intramuscular injection into the anterolateral thigh (vastus lateralis muscle)
• Frequency: Can be repeated every 5-15 minutes if anaphylaxis symptoms persist
• Maximum doses: There is no absolute maximum number of doses; additional doses should be administered as needed if symptoms persist 1

Key Administration Points

• Prompt administration is critical - delays can be fatal 3
• Intramuscular route is preferred over subcutaneous due to faster absorption and more reliable effect 3
• Do NOT inject into buttocks, digits, hands, or feet 2
• Clinical studies show 17% of patients with anaphylaxis require a second dose 1

Intravenous Epinephrine (For Refractory Cases Only)

Intravenous epinephrine should be reserved for:

• Cardiac arrest from anaphylaxis
• Profound hypotension unresponsive to IM epinephrine and fluid resuscitation 4

IV Administration Options

1. Infusion preparation: Add 1 mg (1 mL) of 1:1000 epinephrine to 250 mL D5W (concentration: 4.0 μg/mL)

   • Infuse at 1-4 μg/min (15-60 drops/min), increasing to maximum 10 μg/min if needed 4

2. Alternative preparation: 1:100,000 solution (1 mg in 100 mL saline)

   • Initial rate: 30-100 mL/h (5-15 μg/min)
   • Titrate based on clinical response and side effects 4

3. For cardiac arrest during anaphylaxis:

   • High-dose IV epinephrine: 1-3 mg (1:10,000) slowly IV over 3 minutes
   • Then 3-5 mg IV over 3 minutes
   • Followed by 4-10 μg/min infusion 4, 1

Monitoring and Additional Care

Essential Monitoring

• Continuous cardiac monitoring
• Frequent blood pressure measurements
• Pulse oximetry 1

Common Side Effects

• Anxiety, tremor, dizziness, sweating, palpitations
• Pallor, nausea, vomiting, headache 1, 2

Serious Adverse Effects

• Ventricular arrhythmias (rare with IM administration)
• Rapid blood pressure increases potentially causing cerebral hemorrhage
• Angina 2

Special Considerations

Drug Interactions

• Use with caution with:
  • Sympathomimetic agents (additive effects)
  • Cardiac glycosides (risk of arrhythmias)
  • Tricyclic antidepressants and MAO inhibitors (potentiate effects)
  • Beta-blockers (antagonize cardiac and bronchodilating effects) 2

Post-Administration Care

• All patients should be transported to an emergency department for observation (typically 4-6 hours)
• Extended observation for patients requiring >1 dose of epinephrine due to higher risk of biphasic reactions 1

Common Pitfalls to Avoid

1. Delayed administration of epinephrine (associated with increased mortality)
2. Incorrect route of administration
3. Incorrect injection site
4. Underdosing
5. Overreliance on antihistamines instead of epinephrine as first-line treatment 1

Remember that antihistamines should not be administered before, or in place of, epinephrine but rather used as second-line agents after epinephrine administration 1.